These cards were used by Stewart Brand in managing the creation of the Last Whole Earth Catalog in 1975, which is where I first encountered them.

In the US these cards were sold as McBee Keysort Cards and InDecks Information Retrieval cards.  McBee cards were often used in libraries to keep track of books in interlibrary loan programs.

edge-punched cards sold in theUnited States under the trademarks "Keysort," "E-Z Sort" and "Rocket"and in England as "Paramount" or "Cope-Chat" cards.